Bar for helical springs



'J. F. FLECK 2,157,820

v BAR FOR HELICAL SPRINGS Fil'ed March 1, 1938 VENTOR J6 F Heck T6 NEY Patented May 9, 1939 2457,829 BAR? Fora HELICAL SP R-INGS John F. Fleck, Latrobe, Pa., assig qmo lvefiq la in w o 'P l ewiiYq t Apnlication -March 1,. 1938,; Serial. iNo 193,256- 5 clairns- (Cl. jet 61 'I'hisinventionrelates to spring bars employed as .stock .from' which helical sprin'gsare manuf acturedl.

Thelprincipal object of the invention ,is the I devising. of. a bar of novel characteristics adapted forlliise as stock linthe manufacture. of a range of mel'icalf-springs of. various. diameters .withi'n' predetermined limits, whilemaint'aining the required standard of quality, whereby substantiallyv tthelentirenrangeioi sizes. .oi springs required in commercialusemayl be. manufactured by a proper selection ofiba'rsfromia comparatively Small numberjioflv sizes.

Referring vto .the drawing forming .part of this #1j-application, Figure. lis an elevation of a helical I spring made tfromwa spring lbarlembodying the. present invention; Fig. i 2 ;is an. enlarged, cross. sectionk ofma spring ,bar .,embo.dying vthe present invention; FignB is .ayiewmsimilar to. Fig. 2,. after thebanhasbeen coiled to. form the spring; Figal shoyvsthe contoursof the sectionsof Figsuz' and 3 interposed, the dotted, lines .a showing the extent t oi the def ormation or, upset due,,to coiling and i Fig, ,5 -.;is a view, simila yto ,Fig. .4,. on a ,reduced I] scale showing abar of, conventional square cross secti nbefo ;anda te lc i i a onvent nal. ical prinesarema e om bars, arinus y shap d .in eroes-secti nal c ntour some .7 oily i h. c nt- Lrsa e mposed pf. straight lines hmueheuta thers.v ryi ear throu hout and. wens compris n a v. mnt nation.o straiet and urt il ent ns anc spfth first .twohcontoursi. nel lust ated,r spectiy ly .by a square amine.

m et i 5- i lus r s .a conven ional bar, o square 7 cross section. The stock bar isshown in ,full lines id ndicated by ur ferenc hum a h siele illz ass med be t de.. t.wi form tn inh r c m n helical spring, The sidefi nseq ent r mslthe o t r e, ndl hesides. 4 an he pian l t m r u p ct v fi fie b r 't pri -1 helma Q WHW i Q. thiiough the middle otthe sides 2 and}, dividing The, s a cente' line through the middle of tnegqqa intotwo equal and similar parts.

'1 onstitute .iaaies 0f the ba r ,sectionat es meantime, and the square as to a sj bil-axially symmetric,

l 65 l n ieem kewi e. ideelt ei Square twoedual andsimilar parts. The lines a ferred. to are of similar characteristics in that eachnisllbisaxiallysymmetric and has its geometrical axis. similarly placed;

'lttislwell knownthat; when a bar is coiled about a mandrel to form a helical spring considerable deformationorlupset. of. the metal in the bar takes place} 'Il'ienupset in the square bar is representedindotte djlinesjin ,Fig. 5.

In "the.biraxiallysymmetric typesmof bars the neutral axisiorso called axis of torsion (the axis in ,whi chlthe .Genter of gravity is located), is coincident with th-e geometrical axis, its point of intersectionwith the axes a and b being represented by, the, reference letter at.

Referring again to ,the upset shown in Fig. 5, itgwill be seen that therejis a considerable change n .the confi uration whi .is of a vde rim tal ha. c r.,. heovera he h of th bar i ncreaSed,. ThiswilLnecessitate increasing the free length of the finishedspring to provide for a given mount 1 f. es a edl lection. Th s s an 1 iect onab e characte i ic o a en o l barslas rin tancea l a si av ne a e pe l nd l wera acest l e ll nown that d r spring fl tn-the s eatestl orsi nal ss i u o the inner ce o thes rina. Whe th s u e. s c a has been; coiled into a springit is no longer bix ally nd ifur rm re h a of torsion no longer coincides with v the geometrical axis but has ,beenshifteion account ofthe redistribution oi rnetali tqward the inner face of h r te-l pth' m erqs this ax s s d em. t ai-Qistan esfmm the s des 2 l n 5 face, ;"a.s indicated at ar where the line 2 crosses haa le S i e..-

. csi i nr lih; pf tor ion? ItY Yhas been discoyered; that in a bi-axially o t-s mme r be; tha or iqna s r l greatest at that surface fibre element which is nearest the axis 9? torsign Therefore the axis of torsion wt i elneers e. nn r fac f ev e ina unt. thereof, will be subjected to eatest flit P i: -.i isl aq i vl ke to. be marked 1 1' T y the aiie a r e s si starting and puterjacesl is now nearer the inner ne 2. is employed only to showthe her of sizes (different diameters) of springs. The number of springs that can be made from any onesized bar is dependent upon the limiting qualifications that the bar must have sufficient strength; that the maximum upset must not effect an over-all increase in the height of the bar; and that the axis of torsion of the bar of the spring must be nearer the outer face than the inner face. I

While, with given cross-axial dimensions, the rectangular bar provides maximum metal for the spring, and to cut away the corners, as in the case for instance of hexagonal and octagonal sectional bars, weakens the bar, nevertheless there are certain advantages gained by eliminat ing metal from the inner corners of the bar of the spring, when done according to the present invention, outweighing the benefits gained by the presence of such metal. I

Fig. 2 shows a preferred exemplification of the cross-sectional contour of a bar of the present invention, and this is also shown in full lines in Fig. 4. The horizontal and vertical axes are denoted respectively by the reference letters 0 and d.

The sides 6 and l, designated respectively, for convenience, the inner side of the bar and the outer side of the bar, will, when the bar is coiled into the helical spring, constitute the inner face and the outer face respectively of the spring. The sides 8 and 9 of the bar will constitute the upper and lower faces of the bar of the spring.

The sides 6, l, 8 and 9 however, will be of somewhat different shapes when the bar is coiled into a helical spring, as will later appear. The geometrical axis is indicated by the reference letter 0. and is located similarly to that of the bar of square section of Fig. 5 at the intersection of the axes. These geometrical axes do not change their positions when the bars are coiled.

In the present invention there is an unbalance of the metal of the bar at the opposite sides of the medial plane passing through the Vertical axis (1, the part to the right of this plane, as viewed in Fig. 2, containing more metal than the part to the left. This unbalancing is preferably accomplished by making the side 6 considerably shorter than the side 1, which results in the axis of torsion being disposed to the right of the geometrical axis 0. The axis of torsion, indicated by the letter 1 is positioned at the intersection of the line a with the axis 0. When the bar is coiled the axis of torsion will move toward the inner face of the spring to a position indicated by the reference letter y (in Figs. 3 and 4) where the line 2" intersects the axis 0. It will be noted that in this shifting of the axis of torsion it approaches the geometrical axis 0', and it has been found that the extent of its displacement increases as the diameter of the spring decreases.

It is the purpose of the present invention to produce a sufficient unbalance of the metal to insure this axis of torsion not passingthe geometrical axis, and preferably not reaching the geometrical axis, in themanufacture of any'of the springs that the particular bar is designed for. This will be determined by the extent that the side 6 is shortened, that is to say the amount of metal eliminated from the inner corners. Therefore, within the range of spring sizes that the bar is designed for, the axis of torsion will always be nearer the outer side or face 1 than the inner side or facet, and, as previously stated, during deflection of the spring, the outer face I will take the torsional stress instead of the inner face 6 due to the position of the axis of torsion being nearer the outer face 1. It will be seen, by reference to Fig. 1, that the portion of the spring which is subject to deflection is shaped, in cross section, as shown in Fig. 3, only the ex tremities of the spring bar which do not deflect, being tapered to provide flat upper and lower spring seat surfaces, according to usual practice. In the description and claims this tapering portion is not treated as part of the spring.

It will be noted that with the square sectional bar of Fig. -5, the upset, when the bar is coiled, results in the bar sides 4 and 5 assuming the spring bar face tilted positions illustrated by the dotted lines 4 and 5' respectively. These faces tilt in opposite directions about points substantially in the axis b, which results in the inner portions (portions to the left of axis 1)) diverging from the axis a, thereby increasing the over-all height of the bar, necessitating, for a given amount of designed spring deflection, a corresponding increase in the free length of the finished spring. This is detrimental especially Where, as for example in railroad practice, the space for the spring is generally limited. The outer portions (portions to the right of axis b) converge toward the axis a, which is not detrimental.

Therefore in the preferred embodiment of the bar of the present invention the portion of the bar outwardly from the axis d is preferably made rectangular as shown (Figs. 2 and 4) and the portions of the sides 8 and 9 extending from the axis 01 toward the side I, after the bar has been coiled, converge as shown at 8 and 9' in Fig. 3 and in dotted lines in Fig. 4. The side 7 becomes contracted and slightly concave, as shown at 1 in Fig. 3 and in dotted lines in Fig. 4.

Close adherence to the rectangle is not necessary. The only requirement here is that should; the portions of the sides 8 and 9 outwardly from the axis d be given a divergence from the axis 0, the degree of such divergence should be within proper limits so that, for any spring the bar is designed for, these portions should not inthe finished spring diverge at all, otherwise the overall height in the finished spring would beg-reater than desired, that is to say greater than theheight along the axis d. 0n the other hand-these portions should not be given a convergence to an extent that would defeat the amount of unbalance necessary. In practice the rectangular contour, for manufacturing reasons, is preferable for the portion of the bar disposed utr wardly from the axis d.

The sides 8 and 9 are directed inwardly to meet the extremities of the side 6 respectively at the points e and f. The portions of the sides 8 and 9 extending inwardly, indicated respectively by 8" and 9", are preferably somewhat curved to provide convex faces on the bar. These portions 8" and 9" can, if desired, be of other shapes, such as curved in the opposite direction or straight. In any event, they will, in general direction, converge toward the axis 0 and should begin substantially at the axis (1.

Assuming the side 6 to be straight,'which is the preferable shape, the amount of metal to the left of the axis d will depend upon the length of this side and the shape of the portions 8" and 9".. The degree of convergence of these portions 8" and 9" will of the side 6.

The upset of the bar produced by coiling rebe'governed by the length sults in lengthening the side "6, which is illustrated by the line l2 of Fig. 3 and by the corresponding dotted line of Fig. 4, the points e and I being extended to the positions e? and f, and the portions 18" and '9" then assuming the positions of less convergence, shown respectively by the lines 18and 9" of Fig. 3 and by the corresponding dotted lines of Fig. 4. The requirements here are that the amount of convergence'of the portionssB" and 9 should be sufficient so that the size of the portion of the bar outwardly from the axisid shall be larger than the portion inwardly from the axis .d, for all springs for which the particular type of bar is designed. Furthermore the .degree of convergence of the portions 8 and 9 should be sufficient to insure that the upset produced in making any spring will not result in bringing any part of these portions beyond therespective horizontals at the extremities of the axis d, for many such event the overall fiheig'ht -of the bar would be increased, it being understood that this limitation is approached as the springs for which the bar is designed decrease in diameter. To prevent this the portions 8" and "9" preferably begin to converge approximately at the axis at, or more strictly at the points that will determine the height of'the bar when coiled, and these points should not be at the left of the axis 12.

From the foregoing it will follow that the contour of the section of the bar, made according to this invention, is non-symmetrical on opposite sides of the axis d, and, on account of the respective contours of the sections on opposite sides of the axis d, that portion of the section outwardly from the axis (2 is of greaterv area than the portion inwardly of the axis. Therefore considering the medial plane through this axis at, this plane divides the bar into two unequal portions, the larger portion being that outwardly from the plane. This unbalancing of the metal brings the axis of torsion nearer to the outer face than to the inner face of the bar. The extent of the unbalancing of the metal is such as to space the axis of torsion sufficiently from the said plane of the axis d to prevent its crossing this plane when coiled for any spring of the range of springs the bar is designed for. Likewise the respective contours at opposite sides of this plane of the axis cl are such that for any upset the height of the bar, defined by the axis d, will not be increased. That is to say the height of the bar will not be increased beyond the length of the axis d.

The maximum upset takes place when the bar is coiled for the spring of smallest diameter. Therefore the characteristics of the invention, as to the respective relative weights of the metal of the bar at opposite sides of the aforesaid plane through the axis d, and the contours given the two portions of the bar on opposite sides of the plane through the axis (2, are suitably designed for the spring of smallest diameter within the range for which the bar is designed. One size of bar, made in accordance with the present invention, being suitable for springs within a predetermined range of diameters, a relatively few sizes of bars will be required by a manufacturer for all sizes of springs.

It should be here remarked that Figs. 2-5 are merely diagrammatic, and no attempt is made to show the exact contours of the bars before and after coiling, extent of upset, or exact positions of the axes of torsion.

The invention claimed and desired to be secured by Letters Patent is:

1. A spring bar for coiling into a helical spring comprising an inner face adapted to providethe inner face of said spring; an outer face adapted to provide the outer face of said spring; and connecting faces respectively connecting corresponding ends of said inner and outerfaces, said connecting faces changing their directions at substantially the geometrical medial plane between said inner and outer faces, the portions of said connecting faces extending from said plane to said inner face converging toward said inner face, the contour of said bar being thereby rendered non-symmetrical at opposite sides of said plane, the portion of said bar at the outer face side of said plane being of greater weight than the portion of said bar at the inner face side of .said plane, whereby the axis of torsion of said bar is correspondingly disposed between said plane and said outer face, said converging portions being of suflicient widths and converging to a sufficient extent to maintain said axis of torsion between said plane and said outer face and to prevent the over-all height of said bar from increasing beyond the height at said plane when said bar is upset due to the coiling thereof to form a helical spring of predetermined diameter.

2. A spring bar for coiling into a helical spring comprising an inner face adapted to provide the inner face of said spring; an outer face adapted to provide the outer face of said spring; and connecting faces respectively connecting corresponding ends of said inner and outer faces, the portions of said connecting faces extending from the geometrical medial plane between said inner and outer faces to said outer face being at right angles to said plane, and the portions of the connecting faces extending from said plane to said inner face converging toward said inner face, the contour of said bar being thereby rendered non-symmetrical at opposite sides of said plane, the portion of said bar at the outer face side of said plane being of greater weight than the portion of said bar at the inner face side of said plane, whereby the axis of torsion of said bar is correspondingly disposed between said plane and said outer face, said converging portions being of sufficient widths and converging to a sufficient extent to maintain said axis of torsion between said plane and said outer face and to prevent the over-all height of said bar from increasing beyond the height at said plane when said bar is upset due to the coiling thereof to form a helical spring of predetermined diameter.

3. A spring bar for coiling into a helical spring comprising an inner face adapted to provide the inner face of said spring; an outer face adapted to provide the outer face of said spring; and connecting faces respectively connecting corresponding ends of said inner and outer faces, said connecting faces changing their directions at substantially the geometrical medial plane between said inner and outer faces, the portions of said connecting faces extending from said plane to said inner face being convexly curved and converging toward said inner face, the contour of said bar being thereby rendered nonsymmetrical at opposite sides of said plane, the portion of said bar at the outer face side of said plane being of greater weight than the portion of said bar at the inner face side of said plane, whereby the axis of torsion of said bar is correspondingly disposed between said plane and said outer face, said converging portions being of sufficient widths and converging to a sumcient extent to maintain said axis of torsion between said plane and said outer face and to prevent the over-all height of said bar from increasing beyond the height at said plane when said bar is upset due to the coiling thereof to form a helical spring of predetermined diameter.

4. A spring bar for coiling into a helical spring comprising an inner face adapted to provide the inner face of said spring; an outer face adapted to provide the outer face of said spring; and connecting faces respectively connecting corresponding ends of said inner and outer faces, the

portions of said connecting faces extending from the geometrical medial plane between said inner and outer faces to said outer face being at right angles to said plane, and the portions of said connecting faces extending from said plane to said inner face being convexly curved and converging toward said inner face, the contour of said bar being thereby rendered non-symmetrical at opposite sides of said plane, the portion of said bar at the outer face side of said plane being of greater weight than the portion of said bar at the inner face side of said plane, whereby the axis of torsion of said bar is correspondingly disposed between said plane and said outer face, said convexly curved portions being of sufiicient widths and converging to a sufficient extent to maintain said axis of torsion between said plane and said outer face and to prevent the over-all height of said bar from increasing beyond the height at said plane when said bar is upset due to the coiling thereof to form a helical spring of predetermined diameter.

5. A spring bar for coiling into a helical spring having an inner face adapted to provide the inner face of said spring and an outer face adapted to provide the outer face of said spring, and having maximum height at substantially the geometrical medial plane intermediate said faces, said inner face being of sufficiently less width than said outer face to maintain in said bar, when coiled to form a helical spring of predetermined diameter, the said height of the uncoiled bar and the axis of torsion of the bar disposed nearer said outer face than said inner face.

JOHN F. FLECK. 

